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(No Model.)

J. M. GRIEST.

Tension for Sewing Machines. No. 241,975. Patented May 24,1881.

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. extending fingers e 6.

UNITED STATES {PATENT OFFICE.

JOHN M. GRIEST, OF CHICAGO, ILLINOIS, ASSIGNOR TO WALTER SOATES, WILLIAM F. TRYBER, AND FRANK R. SWEETLAND, OF SAME PLACE, SAID SOATES ASSIGNOR TO SAID TRYBEB AND SWEE'ILAND.

TENSION FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 241,975, dated May 24, 1881. Application filed July 13, 1880. (No model.)

To all whom it may concern Be it known thatI, JOHN M. GRIEST, of Ohicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Tensions for Sewing-Machines,

or which the following, in connection with the accompanying drawings, is a specification.

In the drawings, Figure 1 is a face elevation of the outer face of the removable plate or part of the head of a sewing-machine. Fig. 2 is a like representation of the opposite or inner face of the said plate or part, showing therein the means employed for controlling the pressure of the tension-disks upon the thread. Fig. 3 is a section in the plane of the line as .10 of Fig. 2, and Figs. 4 and 5 are details, in perspective, of the sliding cam and of the tension-spring, respectively.

Like letters of reference indicate like parts.

A is the removable plate or part of the head of a sewing-machine, and B is the tensionregulating screw which enters the said part.

O 0 are the tension-disks, and D is the bolt upon which they are mounted.

E is a flat spring-rigidly fastened at or near its upper end to the interior of the plate A by means of a screw, a. By the words rigidly fastened I do not mean that the said spring is not removable, nor even that it is not movable, but that it should be so held or secured in place that its lower end or working portion cannot be shifted too far from its proper position with relation to the bolt D, as will hereinafter more fully appear, and I employ the screw a for that purpose, for the reason that it furnishes a convenient means for suspending the said spring at a fixed height. The lower part of the spring E is twice split longitudinally, as shown at b I), thus formingatongue, E. A deep notch, 0, is made in thelower end of the tongue E, or, in other words, the said tongue is there forked,'as shown. The springarms d d, thus formed at the sides'of the tongue E, are widened at their lower ends, and e c are notches in the said widened parts. These notches result in the formation of inwardly- Theinner end or part of the bolt'D is grooved, as shown at f, to receive the forked end of the tongue E.

F is a sliding cam, forked and bent at its upper end to enter a groove in the lower or inner end of the screw B, as is clearly shownin Figs.2 and 3. The lower end of the cam F is arched and forked,as is plainly shown in Figs.2and 4, and these forked arms are adapted to enter the notcheseeand pass underneath the fingers e 0.

When the spring E and cam F are arranged in position for use the forked end of the tongue E extends into the groove f, the said spring being secured to prevent it from being displaced. The cam F is arranged over or outside of the spring E, as shown, the upper end of the cam entering the groove in the lower end of the screw B, and the lower or forked end of the said cam passing through the notches e e and underneath the fingers e e, as shown.

It will be perceived from the foregoing description, and from reference to the drawings, that if the screw B be turned in such a direction as to cause it to pass farther into the head of the machine the cam F will be pushed downward, and that, as it passes downward, the fingers e 0 will ride or move up on the arms of the forked end of the cam F, and consequently that the tongue E will tend to draw the bolt D inward with more or less force, thus tightening the disks 0 G and increasing the tension. It will also be perceived that the tension may be lessened by turning the screw B in the opposite direction. The cam F operates as a cam in acting on the spring E, and that part of the said spring which is acted upon directly by the cam moves to a greater extent than that part which directly engages the bolt D.

I deem it best to have the arms 6 6 arranged opposite the axial center of the bolt D, or so that they will stand, as nearly as may be, midwa between the upper and lower sides of the bolt, as shown.

The screw B may be connected to the cam F in any suitable way which will admit of an upand-down movement of the slide by turning the screw correspondingly; but I deem the mode of connection shown and described to be the best.

The cam and spring may be readily applied and removed, and may be constructed with ft cility.

My invention relates, as will be understood by those familiar with tensions for sewing-machines, solely to the parts occupying an intermediate position in relation to the screw B and the bolt D, and I do not here intend to claim, broadly, any other features of construction relating either to the tension or to the head to which it is applied.

I am aware that a springdever engaging the bolt 1) and arranged to be acted upon by the screw 13 has heretofore been employed for the purpose of controlling the tension; but I do not here claim such.

I desire to call particular attention to the fact that the cam F, by being arched,as shown and described, at its lower end, and by there supporting the downwardly-pressin g fingers c 0', will always be held up to its engagement with the screw B, so that there will be no lost motion between the screw and the can], even though the screw only rest against the cam, and without either the screw or the cam being made to otherwise engage each other. This absence of lost motion between these parts in both directions of movement causes the screw B to act at once on the tension as soon as the screw is turned in either direction, and hence the operator is not misled.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-- 1. The combination, in a sewingmachine tension, of the face-plate A, the screw B, bolt D, spring, E, and cam F, the said spring engagiu g the said boltand bearin g upon the said cam, and the said cam operatingin connection with the said screw, substantially as and for the purposes specified.

2. The combination, in a sewing-machine tension, of the face-plate A, the screw B, the grooved bolt D, the flat spriu g E, having therein the forked tongue E, andv the laterally-extending fingers e e, and the cam 1 havingits lower end forked and arched and extending underneath the said fingers, and its upper end arranged for contact with the said screw, substantially as and for the purposes specified.

3. The combination, in a sewing-machine tension,of the faceplate A,the grooved screw B,the grooved bolt D, the split spring E,l1a\'- ing therein the forked tongue E, and the laterally-extending fingers e c, and the cam F, having its upper end forked and its lower end arched and forked,substantinllyzts and forthe purposes specified.

JOHN M. GRIEST.

Witnesses:

F. F. WARNER, H. G. BALLARD. 

